Where are aspx.cs and aspx.designer.cs

I have inherented a web site from someone who is not available any more. In the deployed folder I have Config.aspx there (please see the code). But I can not find the codebehind file. The config page works. Where can I find the .cs files?

Thanks

<%@ page language="C#" masterpagefile="~/Master/StaffPortal.master" autoeventwireup="true"
    inherits="Admin_Config" title="Configuration" codebehind="Config.aspx.cs" %>

<asp:content id="Content1" contentplaceholderid="PageBody" runat="Server">
    <div style="width: 405px; height: 25px" class="GeneralCaption">
    Configuration Parameters
    </div>
    <asp:Table ID="Table" runat="server" Style="width:100%">
    </asp:Table>
    <asp:Button ID="OKButton" runat="server" CssClass="GeneralButton" Text="OK" OnClick="OKButton_Click" />
    <asp:Button ID="CancelButton" runat="server" CssClass="GeneralButton" Text="Cancel" OnClick="CancelButton_Click" />
</asp:content>

Solution

If you cant find them anywhere and you need to get the cs files out of the DLL - here's how:

Get Reflector by redgate, install this add-in: http://www.denisbauer.com/NETTools/FileDisassembler.aspx

Drag the DLL into Reflector then dissemble it using Denis's add-in. All the code behind files will be extracted from the DLL, unfortunately comments will be missing.

UPDATE

These days I use the free tool ILSpy and you can simply save assemblies as projects - its a great way to convert entire projects to different languages.